Serological Profile of Convalescent COVID-19 Patients at an Infectious Diseases Hospital in Nigeria
Adeola Fowotade *
Clinical Virology Unit, Department of Medical Microbiology and Parasitology, Biorepository Clinical Virology Laboratory, College of Medicine, University of Ibadan, Nigeria and Biorepository Clinical Virology Laboratory, College of Medicine, University of Ibadan, Nigeria.
Temitayo Oluwaseun Fasuyi
Clinical Virology Unit , Department of Medical Microbiology and Parasitology, and Biorepository Clinical Virology Laboratory, College of Medicine, University of Ibadan, Nigeria.
Ewean Chukwuma Omoruyi
Biorepository Clinical Virology Laboratory, College of Medicine, University of Ibadan, Nigeria.
Temitope Oluwagbenga Alonge
Infectious Diseases Hospital, Olodo, Ibadan, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Background: IgG antibodies may serve as promising targets to detect and evaluate immune responses against the SARS-CoV-2 virus. Both IgA and IgM antibodies target the spike protein’s receptor binding domain and are rapidly decayed, while IgG antibodies remain relatively stable for longer periods in COVID-19 patients.
Objectives: The current study was designed to detect the presence of SARS-CoV-2 antibodies among convalescent COVID-19 patients and to evaluate the relationship between these antibodies, the symptom grade and their baseline Cycle Threshold (CT) by RT-PCR.
Methods: Eighty-nine convalescent COVID-19 patients on admission were recruited and tested until negative by RT-PCR. Sera obtained from participants were screened for SARS-CoV-2 IgM and IgG antibodies using rapid lateral flow assays.
Results: It was observed that 93,3% and 77,5% respectively had IgM and IgG antibodies against the S1 protein of SARS-CoV-2. Majority (74,0%) presented with mild COVID-19 symptoms with a mean RT-PCR Ct value of 31,4.
Conclusion: Convalescent COVID-19 patients develop a fairly good level of IgG antibodies. The antibody status is not dependent on CT value or symptom grade. However, there was a significant correlation between baseline CT and time taken to test negative by RT-PCR.
Keywords: COVID-19, cycle threshold, antibody, convalescent